##ren ##e first coordinates to ir ##idium in a ligand exchange with the carbon ##yl este ##r oxygen atom before the actual michael addition takes place to the opposite face of the r @ - @ group . = = = en ##ant ##ios ##ele ##ctive variants = = = the development of an en ##ant ##ios ##ele ##ctive na ##zar ##ov cy ##cl ##ization is a desirable addition to the repertoire of na ##zar ##ov cy ##cl ##ization reactions . to that end , several variations have been developed utilizing chi ##ral aux ##ilia ##ries and chi ##ral catalyst ##s . dia ##ster ##eo ##sel ##ect ##ive cy ##cl ##izations are also known , in which extant stereo ##cent ##ers direct the cy ##cl ##ization . almost
##rene first coordinates to iridium in a ligand exchange with the carbonyl ester oxygen atom before the actual michael addition takes place to the opposite face of the r @ - @ group. = = = enantioselective variants = = = the development of an enantioselective nazarov cyclization is a desirable addition to the repertoire of nazarov cyclization reactions. to that end, several variations have been developed utilizing chiral auxiliaries and chiral catalysts. diastereoselective cyclizations are also known, in which extant stereocenters direct the cyclization. almost